The formation of scales in low (matrix) and high (fractures) conductivity zones in oil reservoirs, as well as in oil well drilling systems, production systems, surface equipment, boilers and cooling systems is a major part of the problems found in oil operations.
Most of the scales found in oilfields build up either by precipitation of minerals present in the formation water, or as a result of the produced water oversaturation with mineral components when two incompatible water currents (injection water-formation water) converge at the bottom of the well or at the formation rock. Every time an oil well produces water or uses injection water as a recovery method, the possibility arises for mineral scale to build up.
Formation damage is defined as naturally occurring or induced partial or total obstruction occurring in the rock with the flow of the producing (oil and gas) formation fluids towards the well and vice versa. It is a problem that can happen at different stages of the hydrocarbon exploitation and recovery process, as a result of alterations of the most important petrophysical properties of the rock, such as effective porosity and absolute permeability. Formation damage can be naturally occurring or induced by the fluids used in different operations that are carried out in wells, such as drilling, cementation, completion, repair, production, stimulation treatment and water or gas injection.
Scales can develop in formation pores near the wellbore, which drastically reduces the porosity and permeability of the rock, and also can be present in the production and injection pipelines with the following consequences: damage to the oil reservoir formation, decrease in crude oil production, problems with water injection, flow restriction (pressure losses), well reconditioning works due to reduced production, corrosion in production and injection pipelines and surface equipment, among others. All these problems generate high-cost cleaning treatments, in addition to continuous replacement and maintenance of equipment and pipelines, if the loss of a productive well is not appropriately controlled. The factors that influence the formation of these depositions are: temperature, pressure, flow rate, salinity, concentration of solids dissolved in water, pH, among others.
Scales found in low (matrix) and high (fractures) conductivity zones of the reservoir vary on its composition, which mainly consists of calcium carbonate and calcium, strontium and barium sulfates, as well as iron oxides.
Some mineral scales, such as calcium carbonate (CaCO3), can be dissolved with acids, but this depends heavily on the purity of the mineral, since calcium carbonate generally is combined with other minerals such as calcium sulfate and barium sulfate, which are highly stable in acid environments.
Oil reservoir brines contain particulate matter such as clays and precipitates, mainly calcium compounds. Particles can deposit and build up on surfaces, producing excessive sediments in regions with low velocity water and interfere with the flow of water through the effective porosity of reservoir formations.
For the particular case of the area of services, the formation of deposition in cooling systems is one of the most important problems for production operations throughout the industry. The most important problems caused by scale deposition are: reduced heat transfer, flow restriction (pressure losses), corrosion, among others, which generate costly cleaning expenses, as well as shutdowns and continuous equipment and pipelines maintenance.
In order to offset this kind of problems, a wide range of methods have been used worldwide, with chemical additives standing out for its efficiency and cost, including: scale inhibitors, inorganic salts dispersants and acid solvents, whether in combination or independently.
The most commonly used chemical products include:    1) Sequestering agents. These act through chelation of cations (Ca2+, Ba2+, Sr2+) present in congenital water, so that their solubility products are not exceeded due to concentration. One if the products most widely used is ethylenediaminetetraacetic acid (EDTA).            The disadvantages of this type of products are:            a) Since they work in a stoichiometric manner, a large amount of chelation agent is required, which is undesirable from the economic point of view.    b) They are effective only at low concentrations of dissolved divalent ions.    2) Poly(phosphates). The most widely used are sodium hexametaphosphate (NaPO3)6, sodium tripolyphosphate (Na5P3O10) and several oligo-phosphates, such as those indicated in the U.S. Pat. No. 2,358,222, wherein their structural formulas are the following: Na9P7O22, Na4P2O7, Na6P4O13, Na5P3O10. The inhibitors work in water with moderate calcium concentrations and at a pH close to neutral. The problem posed by poly(phosphates) is that the phosphorus-oxygen (P—O) bond is often reduced and forms orthophosphate ions (PO4−3) (J. Phys. Chem. A 1998, 102, 2838-2841), which may react with calcium ions (Ca2+) to form calcium phosphates (CaHPO4 and Ca3(PO4)2). Reports in the literature (U.S. Pat. No. 4,673,508 “Inhibition of calcium phosphate scale formation with a maleate polymer”, Patent No. EP0267597A2 “Calcium phosphonate inhibition”, U.S. Pat. No. 4,929,632 “Calcium phosphate scale control methods”) have indicated that this type of compounds generates obstruction problems in pipelines, corrosion and decreased heat transfer of equipment when high divalent ions concentrations, high temperature and abrupt pH changes are used (B. P. Boffardi, Materials Performance, 50, 1993).    3) Organophosphonates. These are compounds that contain the phosphorus-carbon bond (P—C) in their structure and work through inhibition mechanisms at the threshold of crystal precipitation and modification. Organophosphonates are widely used as calcium carbonate scale inhibitors; the most common include 1-hydroxyethylene 1,1, diphosphonic acid (a), amino tri-methylene phosphonic acid (b) and diethylenetriamine pentamethylene phosphonic acid (c) (1).
    (1) Phosphonates employed as scale inhibitors a) 1-hydroxyethylene 1,1, diphosphonic acid, b) amino tri-methylene phosphonic acid, c) diethylenetriamine pentamethylene phosphonic acid.
Additionally, there are other organophosphonates with anti-scale applications as indicated in the following patent documents:
U.S. Pat. No. 3,974,090 discloses the synthesis and use of phosphonates having the following structural formula:

U.S. Pat. No. 3,886,205 describes and protects the synthesis and use of a scale inhibitor compound such as the following:

This type of inhibitor presents the advantage that the phosphorus-carbon bond is less susceptible to hydrolysis, but in more severe operating conditions, such as pH sudden changes, high concentration of calcium ions and temperatures above 150° C., they are susceptible to react with calcium ions to form calcium phosphates (G. E. Geiger, Water & Process Technology, 2006, 1-7, “New Non-Phosphorous Calcium Carbonate Inhibitor Reduces Phosphorus Levels and Overcomes Limitations of Phosphonates”; J. M. Brown, W. S. Carey, J. F. McDowell, Corrosion/93, Paper No. 463, 1993; “Development of an Environmentally Acceptable Cooling Water Treatment Program: Non-Phosphorus Scale Inhibitor”; W. Wang, A. T. Kan, M. B. Tomson, SPE 155108, 2012, 1-16; “A Novel and Comprehensive Study and Polymeric and Traditional Phosphonate inhibitors for High Temperature Scale Control”; F. H. Browning, H. S. Fogler, Langmuir 1995, 11, 4143-52; “Effect of synthesis parameters on the properties of calcium phosphonate precipitates”). In addition to this, organophosphonates are susceptible to degradation by oxidizing biocides (Separation Science and Technology, 42, 2007, 1639-1649; “Degradation of Phosphonate-Based Scale Inhibitor Additives in the Presence of Oxidizing Biocides: “Collateral Damages” in Industrial Water Systems”) and to form orthophosphate ions, which react with calcium ions present in water to form calcium phosphates and, therefore, to generate obstruction problems in pipelines and decreased heat transfer in cooling systems.    4) Polymers. Generally, polymeric anti-scaling agents inhibit the formation of scale by chemisorption on the microcrystals active-site facets, and by means of phenomena such as crystal modification, dispersion and inhibition at the precipitation threshold, they prevent the microcrystal growth and clustering.            Some of the most widely used polymers (4) are sodium poly(acrylate), poly(maleic acid), sodium polyvinyl sulfonate and acrylic acid-sodium vinyl sulfonate-derived copolymers.        
    (4). Polymers employed as scale inhibitors: a) sodium poly(acrylate), b) poly(maleic) acid, c) sodium polyvinyl sulfonate and d) acrylic acid-sodium vinyl sulfonate-derived copolymer.
Furthermore, and in order to create enhanced systems, compounds containing several anti-scaling agents have been developed, wherein the following stand out:
European patent No. EP 0256057B1 (“Scale inhibitor”). It describes the use of products to prevent calcium and magnesium scale to build up in evaporation systems, boilers and water-purifying equipment. The patent focuses on the synergistic effect that is generated when three inhibitors are combined. Assessments were performed using different combinations of scale inhibitors in order to find the most effective formulation for the control of CaSO3, CaCO3 and Mg(OH)2 scales. The most effective formulation consists of two polymers (polymaleic acid and sodium styrene sulfonate- and maleic acid-derived copolymer) and an amino phosphonic acid.
European patent application EP0976911A1 (“Scale inhibitors”). It describes a commercial scale-inhibitors combination applied in hydrocarbon extraction and production systems. The compounds contain commercial inhibitors, such as phosphonates, acrylic acid-based copolymers and terpolymers, phosphine acid-carboxylate and phosphate esters combined with amines, since this combination generates an advantage against conventional inhibitors, especially when diethylenetriamine-tetramethylene phosphate is used. This type of amine is characterized for remaining in the fluid at a wide range of temperatures, as well as for being soluble in hydrocarbons such as kerosene, diesel and heavy aromatic naphthas.
U.S. Pat. No. 4,331,792 (“Continuous process for production of copolymer of an alkali metal vinyl sulfonate and acrylic acid”) describes the process for continuous production of the sodium vinyl sulfonate- and acrylic acid-based copolymer, wherein the monomers are mixed and the pH is adjusted at a range of 4-5.5. Additionally, the reaction medium is combined with ammonium persulfate and sodium bisulfite as free radicals-promoting catalyst agents. The reaction is performed in a tubular reactor adiabatically operated at temperatures of 140-220° F. and residence times from 5 to 7 minutes, while the resulting copolymer is removed by precipitation with methanol. The patent also states that the obtained copolymer is useful to prevent the formation of calcium and magnesium scale.
U.S. Pat. No. 4,710,303 (“Low molecular weight polyvinyl sulfonate for low pH barium sulfate scale control”), describes a method to inhibit scaling with sodium polyvinyl sulfonate and compares its effectiveness with regard to other compounds (phosphate esters, sodium hexametaphosphate, 1-hydroxyethylene 1,1, diphosphonic acid, diethylenetriamine phosphonate, acrylic acid-maleic acid copolymer, poly-acrylic acid) in a synthetic brine containing Ba2+ and SO42− ions. Based on this method, sodium polyvinyl sulfonate is effective in the inhibition of scale at pH=2.5-4 conditions and at a temperature of 70° C. at concentrations of 5-10 ppm.
U.S. Pat. No. 5,089,150 (“Method of increasing retention of scale inhibitors in subterranean formations”) describes a method to cross-link acrylate-phosphates based polymers with hydroxide based polymers in order to produce more resistant and compatible compounds in high salinity environments that are characteristic of underground formations. According to said patent, the key point in the inhibitors: stability relies in the polymers cross-linking with polyalcohols, which occurs by esterification of the inhibitors carboxylates and the polyalcohol hydroxides, which results in an increase of the polymeric chains molecular weight, with the same occurring if the polymer is comprised by phosphate groups. As the testing method, they used Berea-type sandstone pre-saturated with congenital water at 90° C. and an injected solution with 2000 ppm of inhibitor dissolved in sea water for each 15 pore volumes.
U.S. Pat. No. 8,215,398 (“Polysaccharide based scale inhibitor”), proposes a method to modify polysaccharides, since derivatives of this type of compounds turn out to be effective in the inhibition of different types of scale. The modified polysaccharide has a molecular weight up to 500,000 AMU and has the features of being biodegradable and resistant to high temperatures as well. It turns out to be useful in the control of corrosion and scale in oil reservoirs due to its high tolerance to organic and inorganic salts such as sodium and potassium chlorides, as well as calcium and magnesium ions.
U.S. Patent Publication No. 2002/0150499A1 (“Oil-soluble scale inhibitors with formulation for improved environmental classification”) provides information about the composition of scale inhibitors with application in hydrocarbon production systems. Formulations contain commercial inhibitors in their acid form, 2-ethyl-hexylamine (2-EHA) and similar amines. The described formulations show an advantage over conventional scale inhibitors, since they are less toxic and more biodegradable.
U.S. Patent Publication No. 2005/0282712A1 (“Scale control composition for high scaling environments”) describes the effectiveness of phosphonate-, sodium sulfonate- and unsaturated dicarboxylate-based polymers, which are useful in the control of BaSO4 and CaCO3 scales in oil reservoir formations.
U.S. Patent Publication No. 2007/0267193A1 (“Stimulating oilfields using different scale-inhibitors”) discloses a method to stimulate an oilfield, using scale inhibitors, with secondary recovery techniques. The method comprises injection of water steam and measurement of inhibitor fractions contained in the recovered fluids.
U.S. Patent Publication No. 2010/0163494A1 (“Preparation of environmentally acceptable scale inhibitors”) presents a method for the control of scale by employing aminoacids to prepare alkyl-phosphonates, which are obtained by controlling the alkyl-phosphonation reaction. According to this proposal, when hydrogens (—H) from each amine-group are substituted with alkyl-phosphonate groups (—R—PO—(OH)2), this type of compounds turn out to be highly effective in the inhibition of CaCO3 and BaSO4 scale. However, the resulting mono-alkylated amino-acids tend to be more biodegradable than the amino-acids di-substituted with alkyl-phosphonates.
U.S. Pat. No. 6,924,253B2 (“Scale removal”) describes a method to remove scale (mainly BaSO4 and CaCO3) within or near the producing well in hydrocarbon recovery processes by using ionic liquids such as: 1-ethyl-3-methyl imidazole tetrachloroaluminate, 1-butylpyridine nitrate, 1-ethyl-3-methyl imidazole tetrafluoroborate and 1-butylpyridinium hexafluorophosphate.
U.S. Pat. No. 7,306,035 (“Process for treating a formation”) proposes a method to increase oil fields production using chemical products in the form of gels wherein these, once inside the formation, encapsulate the oil and facilitate its extraction. On the other hand, this proposal takes into account aspects such as the importance of scale control; thereby it proposes using other substances as additives in the formulation of said gels.
Commonly, some of these chemical substances are scale inhibitors comprising carboxylic and sulfonic groups and combined with molecules composed of carboxylic acids, aminoacids, hydroxycarboxylic acids, hydroxyls, aminophosphates or sulfonates groups.
European patent EP 1639228B1 (“Method for stimulating an oilfield comprising using different scale-inhibitors”) proposes the production of crude oil by injecting water steam in the producing zone as displacing fluid and to recover it as an oil-bearing fluid, with the intention of this proposal being to perform the fluid injections in different segments of the producing zone. It also contemplates the use of scale inhibitors at different concentrations and injected directly and/or diluted.
In general, this is a production method wherein the injection of the inhibitor in different zones allows for an improvement in scaling control.
By virtue of the demands in hydrocarbon production processes, as well as in the area of services, specifically cooling systems and boilers, this type of substance must be able to work under severe operation and low toxicity conditions.
Therefore, the development of enhanced scale inhibitors and dispersants is a goal that is continuously pursued worldwide, and it is the purpose of the present invention.
It is worth mentioning that supramolecular chemistry is the part of chemistry that takes care of the study of systems that involve molecule or ion aggregates that are bound through non-covalent interactions, such as electrostatic interactions, coordination bonds, hydrogen bonds, π-π interactions, dispersion interactions and solvophobic effects.
Supramolecular chemistry can be divided in two large areas: 1) Host-Guest Chemistry and 2) Self-assembly. The difference between these two large areas is a matter of size and form; where there is no significant difference in size and none of the species acts as host to the other, the non-covalent bonding between two or more species is termed self-assembly.
From an energetic point of view, supramolecular interactions are much weaker than covalent bondings, which are in the energetic range of 150 to 450 Kj/mol for simple bonds. The non-covalent interactions energetic range goes from 2 kj/mol for dispersion interactions to up to 300 kj/mol for ion-ion interactions (Table 1), and the sum of several supramolecular interactions can produce highly stable supramolecular complexes.
With regard to the formation of supramolecular complexes from the interaction of polymers or organic compounds with mineral salts with scaling properties, the following examples are found in literature:
The article “Binding of Calcium and Carbonate to Polyacrylates” (Journal of Physical Chemistry B 2009, 113, 7081-7085) proposes that the interaction of polyacrylates with calcium carbonate is a thermodynamically-favored process that results in the formation of complexes, which are characterized for preventing the growth of calcium carbonate crystals.
TABLE 1Supramolecular Interactions StrengthInteractionStrength (Kj/mol)Ion-ion200-300 Ion-dipole50-200Dipole-dipole5-50Hydrogen bond 4-120Cation-  5-80  -  0-50Van der Walls<5HydrophobicRelated with the solvent-solvent interaction energy
The article “Control of Crystal Nucleation and Growth of Calcium Carbonate by Synthetic Substrates” (Chemistry of Materials 2001, 13, 3245-3259) indicates that calcium carbonate crystals nucleation and growth can be controlled by using synthetic substrates and that this process involves the formation of supramolecular complexes resulting from the adsorption process of monomers or carboxylated polymers on calcium carbonate surfaces.
The article “A new Design Strategy for Molecular Recognition in heterogeneous Systems: A Universal Crystal-Face Growth Inhibitors for Barium Sulfate”, Peter V. et al. (J. Am. Chem. Soc. 2000, 122, 11557-11558), indicates that the strategy for the design of new additives that control scaling problems is based on molecular recognition and that polyaminomethylphosphonates derived macrocycles control the growth of barium sulfate crystals through the formation of complexes.
The article “At the Interface of Organic and Inorganic Chemistry: Bioinspired Synthesis of Composite Materials” (Chemistry of Materials 2001, 13, 3227-3235) indicates that the design of biomineralization processes artificial models has led to the combination of inorganic materials investigation and organic supramolecular chemistry, and that polyamides ligands with carboxylates interact with calcite crystals. Furthermore, the article mentions that copolymers in block with two hydrophilic groups have been successfully used to modulate the morphology of inorganic materials such as calcium carbonate and barium sulfate.
Computational chemistry is a widely used tool worldwide to predict the stability and structure of chemical systems with enhanced potential properties and has found application at industrial level in the development of quantitative structure-activity relationship studies. Computational calculation methods that have been used for this purpose include molecular mechanics methods, quantum methods, which comprise semi-empiric and ab-initio methods, and the density functional theory methods. As examples in literature demonstrating the use of computational chemistry to accurately predict supramolecular interactions in chemical systems and/or thermodynamic and kinetic aspects of chemical processes, the following articles can be quoted: 1) Cornucopian Cylindrical Aggregate Morphologies from Self-Assembly of Amphiphilic Triblock Copolymer in Selective Media (Journal of Physical Chemistry B, 2005, 109, 21549-21555), 2) Density Functional Calculations, Synthesis, and Characterization of Two Novel Quadruple Hydrogen-Bonded Supramolecular Complexes (Journal of Physical Chemistry A, 2004, 108, 5258-5267), 3) Strong Decrease of the Benzene-Ammonium Ion Interaction upon Complexation with a Carboxylate Anion (Journal of American Chemical Society, 1999, 121, 2303-2306).
It is important to highlight that none of the abovementioned references deals with obtaining random copolymers based on itaconic acid or isomers and sodium alkenyl sulfonates and the use thereof to inhibit scale of minerals such as calcium carbonate and barium, strontium and calcium sulfates that occur due to water incompatibility (injection water-formation water) in an oil reservoir, as well as in the production rig of an oil well, and as dispersants of clays, calcium carbonate, barium, strontium and calcium sulfates and iron oxides present in oil facilities. Additionally, there is also no mention about their use in cooling systems and boilers present in the oil and chemistry industry.